Embodiments of the invention relate to sensing devices, and particularly to two-wire sensing devices.
Level sensing devices, such as fuel level sensors and the like, are often connected to a gauge, which provides a visual indication of the amount of liquid or material in a tank, hopper, or similar container. A typical fluid level sensor includes a float that floats or rests on top of the fluid or material in a tank and a potentiometer. The potentiometer generally includes a tap that is mechanically connected to the float. When the float moves (such as due to a change in the level of the fluid in a tank) the tap moves. Movement of the tap causes a change in the resistance of the potentiometer. The potentiometer is connected in a circuit such that the change in resistance causes a change in the magnitude of the current in at least part of the circuit. The change in current magnitude changes, for example, the position of a needle in an analog gauge. Thus, as the fluid level changes, the reading of the gauge changes.